Mechanical chair



Filed Feb. 6, 1953 3 Sheets-Sheet l I l INVENTOR. l8 a 20 36 24 HOMERN/EDERHAUSER W j: -M iad I ATTORNEYS March 13, 1956 Filed Feb. 6, 1953H. NIEDERHAUSER 2,738,000

MECHANICAL CHAIR 3 Sheets-Sheet 2 INVENTOR. HOMER N/EDERHAUSER ATTORNEYSMarch 13, 1956 H. NIEDERHAUSER 2,738,000

MECHANICAL CHAIR Filed Feb. 6, 1953 a Sheets-Sheet 5 IN V EN TOR. HOMERN/E DE RHA USE R ATTORNEY United States PatentO MECHANICAL CHAIR HomerNiederhauser, Berne, Ind.

Application February 6, 1953, Serial No. 335,420

6 Claims. (Cl. 155-116) The present invention relates to a mechanicalchair, and more particularly to a chair having a backrest which ispositionable between full upright and reclined positions.

Many different types of mechanical chairs in which the backrest ismovable to full reclining position have been proposed and used; however,certain disadvantages are inherent in these prior art designs, whichinclude the disadvantage of the backrest not conforming to the movementof an individuals torso as he moves backwardly or forwardly with thebackrest. movement is easily detected by sitting in a prior art chairwith the backrest in full upright position, then allowing the backrestto swing backwardly with the individual maintaining relaxed contacttherewith. As the back swings downwardly, a relative motion occursbetween the backrest and the individual which is evidenced by theindividuals clothes being drawn or gathered uncomfortably upwardly. Thisrequires that the individual lean forwardly sufliciently to allow hisclothes to readjust.

This unnatural By analyzing this relative motion between the backrestand the individual, it has been discovered that the motion of thebackrest is unnatural, meaning that the backrest motion does not conformto that of the motion of an individuals back as he swings from anupright sitting 1 position to a full reclining position.

It is therefore an object of this invention to provide a mechanicalchair having relatively movable backrest and seat portions which aremovable from full sitting to full reclining position and which conformssubstantially to the motion of an individuals torso between full sittingand full reclining position.

It is another object of this invention to provide a mechanical chairhaving a backrest which is positionable between full sitting and fullreclining positions and which may be comfortably operated by anindividual by merely exerting operating force on the backrest.

Other objects will become apparent as the description proceeds.

To the accomplishment of the above and relatedobjects, my invention maybe embodied in the forms illustrated in the accompanying drawings,attention being called to the fact, however, that the drawings areillustrative only, and that specific change may be made in the specificconstructions illustrated and described, so long as the scope of theappended claims is not violated.

In the drawings: i

Fig. 1 is a perspective view of a typical chair of this invention;

Fig. 2 is a top plan cut-away view of the chair of Fig. 1 showing themechanism therein;

Fig. 3 is a perspective illustration of a part of the mechanism foroperating the chair; and

Figs. 4, 5 and 6 are side elevations of the same chair with the fabriccovering removed showing the chair adjusted to full sitting,intermediate reclining," and full reclining positions.

With reference to the drawings, and more particularly to Fig. 1, atypical-chairwhich may incorporate. this invention is shown as being ofthe overstuffed design, but it will of course be understood, that anychair having a seat and backrest may be designed to incorporate theoperating features of this invention. The chair comprises a stationaryframe generally indicated by the reference numeral 10, a seat 12 and aswingable backrest 14. The frame 10 is so designed as to provide twoupright support members 16 at the rear thereof (one such support 16being shown in Fig. 3) which must be of a suitable strength and rigidityas will become apparent from the following description. A pivot plate 18is mounted on the inner lateral side of the frame support 16, and inquality merchandise, will be preferably fabricated of sheet metal. Acantilever 20 is pivoted at A to the plate 18 and extends forwardlytoward the front of the chair. A lever 22 is pivoted intermediate itsends to a point B on the cantilever 20 intermediate the latters ends.Another common lever 24 is pivoted intermediate its ends at C to theplate 18 so as to lie in the general plane of the two levers 20 and 22.A support plate 26 having suitable fastening apertures 28, is fixedlysecured to the left end of the common lever 22 and projects inwardly ofthe chair at right angles to the general plane of levers 20, 22, 24. Asseen more clearly in Figs. 4, 5 and 6, this backrest support 26 is setat an acute angle on the lever 22.

Further describing the leverage system, a link 30 pivotally connects theadjacent ends of the left-hand lever arms of the two levers 22 and 24together, and a similar link 32 pivotally connects the adjacent ends ofthe opposite lever arms together also. As will become apparent from thedescription to follow, one or the other of these two links 30 and 32 maybe removed without altering the operation of the system.

A third link 34 connects the right-hand end of the two levers 20 and 24together, and a depending strap 46 is connected at its upper extremityto the outer or righthand end of the lever 22. It will, of course, beunderstood that the linkage mechanism just described is duplicated'onthe opposite side of the chair as illustrated more clearly in Fig. 2,with the lower extremities of the two depending straps 36 being tiedtogether by means of a horizontally extending strap 38 having suitablepivot connections 40. This strap 38 passes underneath the rear portionof the seat 12 for swinging the seat about suitable hinges 42 mountedbetween the front edge of the seat 12 and the chair frame 10. As isshown more clearly in Figs. 4, 5 and 6, the backrest 14 is rigidlymounted on the support 26 of the lever 22. Also as shown in Figs. 4, 5and 6, the seat 12 is shown as being comprised of suitable conventionalsprings and pads indicated by dashed lines at 44 and 46 respectively.The seat surface is indicated by the reference numeral 48.

With the backrest in full upright position, the operating linkage willconform substantially to that shown in Figs. 3 and 4. With the backrestswung to a position approximately midway between full sitting andreclining positions, it will assume the position illustrated in Fig. 5.In Fig. 6, the backrest and seat are moved to full reclining orhorizontal positions.

The operation of the leverage system is as follows:

Starting from a full sitting position, and exerting a slightcorresponding motion of the respective right-hand ends he. ev s- .2.-nd. ir ic he r ht nd, f. t e.

cantilever 20 swings upwardly, the rear of the seat 12 will be liftedabout its fulcrum 42 by reason of the upward motion-ofthe-sling-comprisedof the straps36. If continuedqforce is exerted on'theupper tions which substantially conform :to the movement of apersonsbody thereby making the feeling of reclining in the chair completelynatural and comfortable without the usual gathering or slipping of thepersons clothes. The motion of the backrest may be easily plotted by theuse of geometry and it will be found that such plot will show generallythat the backrest 14 moves longitudinally downwardly as it is beingswung backwardly while the lower extremity is simultaneously describingan arc in a downward and forward direction. This motion of the backrestmay be more easily envisaged by considering the path of .movement of thepoint of intersection or attachment between the backrest support 26 andthe left end of the lever 22. Considering Figs. 4 and 5, as the backrest14 is swung rearwardly, the motion of the lever 22 is transformed into aleverage reaction which swings the outer end of the lever 20 upwardly.This results in the pivot point B being swung upwardly,

and with the point Bbeing below the pivot point A asshown, the support26 will move generally forwardly as well as downwardly.

The exact path of movement of the backrest 14, and the seat 12 as well,will depend upon the lengths of the respective lever arms and the pointsof connection be-. tween the levers and the respective links. However,by making a geometric analysisof the swinging motion of the human bodyas it moves from full sitting to fullreclining positions, it is possibleto arrange the leverage system to conform substantially thereto. Ananalysis shows that by varying the relative positions of '-the.con-.nections between the link 34 and the levers 20 and 24, the distancethrough which the back support 26'travels may be varied. The pathfollowed by the backrest support 26 is partially dependent upon theposition of pivot B on the cantilever 20 and the links of the lever armsof lever 22. A general analysis shows that as the lever 22 is swungcounterclockwise, the sling 36,- 38 moves upwardly. Therefore, more orless mechanical advantage as desired, in operating the chair may begained by adjusting-the sizes of the lever armsof the lever 22,lengthening the left-hand leverarmserving'to increase the mechanicaladvantage.

While the sling 36, 38 has beenshown as being fastenedto the outerextremity of thecantilever 20, the system will operate equallysatisfactorily by fastening the upper ends of the straps 36 to theright-hand end portionsofthe lever 24. The only requirement in thisrespect is that the movement of the seat 12 be made to comfortablyconform to the movement of the backrest 14and hence the movement of thehuman body.

As is apparent from the foregoing description, the backrest 14 may beoperated either upwardly or downwardly by exerting a corresponding forceon the backrest 14. Ease of operation may be adjusted by introducingfriction at the various joints and pivots in the leverage system, aswell as adjusting the leverage ratios of the leverage system.-

While the exact mot-ionof the chair parts-will vary. with designpreferences, the -means is hereby presented, underthis inventionbywhich-suitable, body-conforming.

motion may-be built into a mechanical chair.

Another possible alternative-to thestructureillustrated in the drawingsis one in which the link 30 is cut off adjacent the pivot B and the link34 is eliminated, the strap 36 being affixed to the-lever 24 a suitabledistance to the right of pivot C.

Design and operational preferences will dictate the lengths of thevarious levers and links in order to achieve the desired character ofrelative movement between the backrest and the seat.

What is claimed is:

l. A mechanical chair comprising a seat and a backrest which are movablerelative to each other into full sitting or full reclining position, astationary'support, a system of levers pivotally carried by said supportand operatively connecting said seat and backrest together, said systemof levers including a first cantilever pivoted at one end on saidsupport, a second lever pivoted intermediate its ends on said cantileverand being fixedly secured to said backrest, leverage meansinterconnecting one end of said second lever withthe outer end ofsaidcantilever, and means operatively connecting said cantilever to saidseatwhereby said seat exertsa gravitational force-on said cantilever, saidsystem of levers being op erable to swing the .backrest from upright toreclining position in accordance. with a motion which carries the lowerendof the backrestdownwardly and forwardly while; the backrest itself ismoving longitudinally downwardly.

2.. A mechanical chair comprising a seat and a backrest which aremovable relative to each other into full sittingv or full recliningposition, a stationary support, a system of leverspivotally carried bysaid support and operatively connecting said. seat and backresttogether, saidsystem oflevers including a first cantilever pivoted atoneend on. said support, a second lever pivoted intermediate its; ends onsaid cantilever and being fixedly secured to said; backrest, a'thirdlever pivoted intermediate its ends to said support,.a first rigid linkinterconnecting two: adjacentends of said'second and third leverstogether whereby clockwise motion of one will impart clockwise motion tothe other, a strut interconnecting the. outer end of said cantileverwith the adjacent end of said third lever whereby both levers will movetogether inthesame'rotational direction, and linkage meansoperativelycoupledbetween the outer end of said cantilever and saidseat, said system of levers thereby being operable-to swing the backrestfrom upright to reclining position in. accordancewith a motion whichcarries the lower end of the backrest downwardly and forwardly while thebackrest itself is moving longitudinally downwardly.

3. A mechanical chair comprising a seat and a backrestwhich-are movablerelative to each other into full sitting or full recliningposition, astationary support, a,

system of levers-pivotally carried by said support and operativelyconnecting said seat and backrest together,-

said=system of lovers including a first cantilever pivoted at one end onsaid support, a second lever pivoted intermediate-its ends onsaidcantilever and being fixedly eratively coupled between the outer endof said canti-v lever and. saidseat, said system of levers thereby beingoperable to swing the backrest from'upright to reclining position inaccordancewitha motion which carries the lowerxend; ofthesbackrestdownwardly and forwardly while the backrest? itselfis'moving longitudinally doWn.-. wardly, said seat rising during thedownward swing of.

said backrest.

4.; A mechanical; .chainzcomprising a .seat and. a back-1:-

rest which are movable relative to each other into full sitting or fullreclining position, a stationary support, a system of levers pivotallycarried by said support and operatively connecting said seat andbackrest together, said system of levers including a first cantileverpivoted at one end on said support, a second lever pivoted intermediateits ends on said support, a second lever pivoted intermediate its endson said cantilever and being fixedly secured to said backrest, a thirdlever pivoted intermediate its ends to said support, a first rigid linkinterconnecting two adjacent ends of said second and third leverstogether whereby clockwise motion 'of one will impart clockwise motionto the other, a strut interconnecting the outer end of said cantileverwith the adjacent end of said third lever whereby both levers will movetogether in the same rotational direction, and linkage means operativelycoupled between the outer end of said cantilever and said seat, saidsystem of levers thereby being operable to swing the backrest fromupright to reclining position in accordance with a motion which carriesthe lower end of the backrest downwardly and forwardly while thebackrest itself is moving longitudinally downwardly, said seat beingpivoted at its front edge, the rear portion of said seat being lifted bysaid linkage means as said backrest swings downwardly.

5. A mechanical chair comprising a seat and a backrest which are movablerelative to each other into full sitting or full reclining position, astationary support, a system of levers pivotally carried by said supportand operatively connecting said seat and backrest together, said systemof levers including a first cantilever pivoted at one end on saidsupport, a second lever pivoted intermediate its ends on said cantileverand being fixedly secured to said backrest, a third lever pivotedintermediate its ends to said support, first and second linksinterconnecting adjacent respective ends of said second and third leverstogether whereby clockwise motion of one willimpart clockwise motion tothe other, a strut interconnecting the outer end of said cantilever withthe adjacent end of said third lever whereby both levers will movetogether in the same rotational direction, and linkage means operativelycoupled between the outer end of said cantilever and said seat, saidsystem of levers thereby being operable to swing the backrest fromupright to reclining position in accordance with a motion which carriesthe lower end of the backrest downwardly and forwardly while thebackrest itself is moving longitudinally downwardly.

6. A mechanical chair comprising a seat and a backrest which are movablerelative to each other into full sitting or full reclining position, astationary support, a system of levers pivotally carried by said supportand operatively connecting said seat and backrest together, said systemof levers including a first lever pivotally mounted on said support andhaving an operative connection with said seat, a second lever pivotallymounted on said first lever and carrying said backrest, meansinterconnecting said first and second levers together for transmittingmotion from said second lever to said first lever, said system of'leversbeing operable to swing the backrest from upright to reclining positionin accordance with a motion which carries the lower end of the backrestdownwardly and forwardly while the backrest itself is movinglongitudinally downwardly.

, References Cited in the file of this patent UNITED STATES PATENTS

